The association of smoking and acne in men in Hong Kong and in India: a retrospective case-control study in primary care settings.

Previous studies on the association of smoking with acne vulgaris have reported conflicting results. The objective of this study was to investigate such an association. Our setting was three primary care practices in Hong Kong and one primary care practice in India. Patient characteristics in all four practices are similar. All medical records in these practices incorporate a section in which the smoking habits of each patient is routinely documented. We searched our database and retrieved 632 records of patients with acne seen in the previous 5 years. We also retrieved 632 records of age- and sex-matched controls. Fifty-three out of 379 male patients with acne and 25 out of 379 male controls were smokers (P = 0.001; OR, 2.3; 95% CI, 1.4-3.8). Six out of 253 female patients with acne and three out of 253 female controls were smokers (OR, 2.0; 95% CI, 0.5-9.4). We conclude that smoking is likely to bear a positive correlation with acne for men. Our numbers are too small for a definite conclusion to be drawn for females.